1. Technical Field
The present invention relates to an apparatus and method of processing an image.
2. Description of the Related Art
In a computer system serving as a host for a printer, a monitor or the like (hereinafter, referred to as a “representing device”), an image representing device controls operation of the representing device in response to an instruction from a user. Specifically, the image representing device creates data for an image including pictures, texts, or the like that can be processed by the representing device (hereinafter, referred to as “data to be represented”), and transmits the data to the representing device so that the data can be represented on a representation medium such as a screen or papers.
The represented image may be a color image that may be represented in RGB. According to a user's preference or performance of a representation medium, the image may be represented as a grayscale image that is a black-and-white image. Here, the grayscale image refers to an image having pixels each represented by single hues having a brightness (luminance) value, for example, from 0 to 255.
Normally, a grayscale image may be created by using only a luminance component in a color space such as YCBCR, YPBPR or hue saturation lightness (HSL). For example, an image processing apparatus may convert an original RGB color space into the luminance component using the Y component of YCBCR color space.
However, since a conventional method of creating a grayscale image converts, for example, an image in a RGB color space into the image in the Y component while discarding a CBCR component, when objects have the same luminance and different colors, a grayscale image is created with the objects having the same luminance, such that objects cannot be discriminated in a represented result. FIG. 1a illustrates an image consisting of small squares having various colors, and FIG. 1b illustrates a result of representing the image of FIG. 1a using the only Y component.
Even when colors have some differences in luminance, as shown in FIG. 1b, it is generally difficult to discriminate among small squares due to lost chrominance components.